Comparative Pharmacokinetic Studies of One‐Month Donepezil IM Depot and Once Daily Oral Tablet in Healthy Male Volunteers

Background This study is to evaluate the safety and tolerability of single dose of one‐month donepezil IM depot (GB‐5001) in healthy male volunteers and to compare pharmacokinetic parameters of 70mg donepezil IM depot and 10mg once daily oral tablet (Aricept®) in human. Method In this phase 1, a randomized, double‐blind, placebo‐controlled, dose‐escalation study, 48 healthy subjects were randomized to single dose of Aricept tablet or placebo or GB‐5001 (70mg or 140mg or 280mg) for 64 days. In this study, safety and tolerability of 70mg donepezil IM depot were examined by monitoring adverse events and vital signs. PK parameters such as AUCt, AUCinf, Cmax and Tmax were compared by measuring donepezil concentration after a single dose of 70mg IM depot and 10mg oral tablet. Result A single dose of 70mg donepezil IM depot showed no significant adverse events and was well tolerated in healthy male volunteers. In 70mg GB‐5001, all the subjects had measurable concentrations up to 1512 h post dose. The geometric mean of PK exposure parameters are 6482.82 h*ng/mL, 6604.01 h*ng/mL and 11.40 ng/mL for AUCt(0‐1512h), AUCinf, and Cmax, respectively. The median peak concentration (Tmax) was observed at 432h post dose. In 10mg oral Aricept, all the subjects had measurable concentrations up to 240 h post dose. The geometric mean of PK exposure parameters are 656.84 h*ng/mL, 751.34 h*ng/mL and 17.68 ng/mL for AUCt(0‐240h), AUCinf, and Cmax, respectively. The median peak concentration (Tmax) was observed at 2.25 h post dose. Conclusion A single dose of 70mg donepezil IM depot was found to be safe and well tolerated in healthy male volunteers. The pharmacokinetic results of 70mg donepezil IM depot showed stable donepezil blood concentration for more than one month without burst drug release, and showed comparable unit dose drug exposure not lower than that of once daily 10mg oral formulation. Through the PK results for additional higher doses and multiple PK simulations, optimal once monthly dose of donepezil IM depot could be suggested which will be bioequivalent to 10mg once daily tablet.